Preparation of activated carbons from rambutan (Nephelium lappaceum) peel by microwave-induced KOH activation for acid yellow 17 dye adsorption

A novel agricultural waste, rambutan (Nephelium lappaceum) peel was used as the precursor for preparation of activated carbon by chemical assisted KOH activation. Microwave heating was employed for activation, and thereby considerably reduced the activation time. The prepared activated carbon was characterized by pore structural analysis, zero-point-of-charge (pHpzc), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The adsorption performance for the removal of acid yellow 17 (AY 17) was investigated. The effects of contact time, initial dye concentration and pH on the adsorption process were studied. The equilibrium time was 4h, and results indicated high adsorption capacity, even at high initial dye concentrations. Kinetic studies showed that pseudo-second-order kinetic model better described the adsorption process. The experimental adsorption isotherms were modeled using the Langmuir, Freundlich and Temkin equations. The best fit was obtained with the Langmuir isotherm model, implying that the adsorption of AY 17 onto RPAC from the aqueous solutions proceeds by a monolayer formation. The maximum monolayer adsorption capacity of AY 17 was 215.05mgg-1. © 2014 Elsevier B.V.